Guillaume de Jumièges records that "Osbern, intendant de la maison du prince [Guillaume II Duke of Normandy] et fils d'Herfast" was murdered at Vandreuil in the early years of the duke's reign by "Guillaume fils de Roger de Montgomeri"[18].

m EMMA d'Ivry, daughter of RAOUL d'Ivry Comte de Bayeux & his wife --- (-after [1067]). She is named as mother of Guillaume and Osbern in the donation to Sainte-Trinité de Rouen, dated to 1038 or after, which they made jointly for the soul of their father "Osbern cognomento Pacifici"[19]. "Emma matre eorum [Willelmi et Osberni]" witnessed a charter dated 1038 or after[20]. "Emma Osberni dapiferi uxore" is named as "dominis mei" with her two sons in the undated charter of Ansfredus[21]. "Emmæ matris eius" signed a charter of "Erchenbaldo filio Erchenbaldi vicecomitis", dated to [1067], immediately after "Willelmi filii Osberni"[22]. Osbern & his wife had three children:

i) GUILLAUME FitzOsbern (-killed in battle Cassel, Flanders 22 Feb 1071, bur Abbaye de Cormeilles). Guillaume de Jumièges names "Guillaume fils d'Osbern, proche parent du duc Guillaume", recording that he built the monasteries at Lire and Corneilles[23]. He is named as brother of Osbern, son of Emma, in his donation to Sainte-Trinité de Rouen dated 1038 or after, made jointly with his mother and brother[24]. "Willelmi filii Osberni" witnessed two charters dated 1035 or after and 1038 or after[25]. "…Guillelmi filii Osberni…" witnessed the charter dated 1054 under which Guillaume II Duke of Normandy confirmed the donation of "terram…Sancta Columba…dedit Niellus clericus" to the abbey of Mont-Saint-Michel[26]. "…Willelmi filii Osberti, Rotgerii de Monte Golmerii, Richardis vicecomitis Abrinchensis…" witnessed the charter dated [1055/56] under which Guillaume II Duke of Normandy "in pago…Constantino, villam…Flotomannum" to Saint-Florent de Saumur[27]. "…Guillelmus filius Osberti…Guillelmus filius Guillelmi filiii Osberti…" witnessed the charter dated to [1060] under which Guillaume II Duke of Normandy granted "Brenerias" to the abbey of Bayeux[28]. "Willelmus filius Osberti…" witnessed the charter dated 29 Aug 1060 under which "milite…Richardo…fratribus Willelmo…atque Balduino" donated "Gausberti Villa" to Chartres Saint-Père[29]. The Chronique de Normandie, based on le Roman de Rou, records that William I King of England made "le Conte Rogier de Montgomery et Guillaume le filz Osber" his two "Marechaulx d´Engleterre" after the conquest of England[30]. "Willelmi filii Osberni" signed a charter of "Erchenbaldo filio Erchenbaldi vicecomitis" dated 1067 or after[31]. "Willelmus comes filius Osberni dapiferi" made a donation to Sainte-Trinité de Rouen dated 1068[32]. He was rewarded for his part in the conquest of England with estates in the Isle of Wight and county of Hereford, thereby becoming Earl of Hereford.

ii) OSBERN (-1101). He is named as brother of Guillaume, son of Emma, in his donation to Sainte-Trinité de Rouen dated 1038 or after, made jointly with his mother and brother[33]. "Osberni frater eius [Willelmi]" witnessed a charter dated 1038 or after[34]. Chancellor of England. Bishop of Exeter 1072[35].

iii) EMMA . "Emma conjux eius" donated land belonging to the castle of Vernon to Sainte-Trinité de Rouen jointly with her husband, dated 1066[36]. Guillaume de Vernon, his son Hugues and his wife Emma donated property to Rouen Holy Trinity, confirmed in the charter dated to [1067][37]. Her parentage is confirmed by a charter of Carisbrooke Priory, Isle of Wight which names “Johannem et Ricardum” as the two sons of “Willielmum filium Osberni marescallum…comitem Herefordiæ” who predeceased their father, and records that their inheritance went to “Ricardo de Rivers, nepoti prædicti Willielmi filii Osberni, tunc comiti Exoniæ”[38].